Polarized electromagnetic relay



June 9, 1964 s. J. HARRIS 3,136,873

POLARIZED ELECTROMAGNETIC RELAY Filed Nov. 30. 1960 INVENTOR SAMUEL J. HARRlS A TORNE S 3,136,873 POLARIZED ELECTROMAGNETIC RELAY Samuel J. Harris, West Collingswood, N.J., assignor, by mesne assignments, to Thompson .Ramo Wooldridge Inc., Euclid, Ohio, a corporation of Ohio Filed Nov. 30, 1960, Ser. No. 72,772 9 Claims. (Cl. 200-87) This invention relates to circuit controls and particularly to circuit breakers including an electromagnetically releasable magnetic means for holding the electrical circuit closed.

It is the primary object of the present invention to provide a circuit breaker which is highly reliable and versatile. In accordance withthe invention a magnetic circuit, which includes a permanent magnet 'and the core of an electromagnet, is used to hold a switch closed against the bias of a mechanical means. The electromagnet is energized in response toan excess current therethrough to neutralize the magnetic circuit to permit the mechanical means to open the switch and thus break the circuit to be controlled. As will appear, the switch which is actuated may close as well as open one or more circuits but for simplicity of description reference will be made to the device as a circuit breaker since this would be its widest use.

The general objects of the invention as well as subsididiary objects particularly relating to details of construction and operation will become apparent from the following description, read in conjunction with the accompanying drawing, in'which:

FIGURE 1 is an elevational view of a circuit breaker provided in accordance with this invention;

FIGURE 2 is an elevational view of the same as viewed from the right side of FIGURE 1;

FIGURE 3 is a sectional view taken on the plane indicated by the lines 33 of FIGURE '1; and i FIGURE 4 is a sectional view taken onthe plane indicated by the lines 44 of FIGURE 1.

The circuit breaker in accordance with this invention comprises a frame 2 having a mounting leg 4 joined at right angles with a supporting plate 6. Leg 4 has a pair of threaded bosses 8 for use in mountingthe frame.

A switch 10 is mounted on frame 2 by means of a pair of pins 12 and 14 which have threaded ends and which project through openings in plate 6 for threaded engagement with mounting nuts 18. Pin 12 is a shoulder pin and at its mounting end extends through an opening in plate 6 to be fixedly mounted thereon by a nut 18.

As is best shown in FIGURE 4, the mounting end of pin 14 extends through an oversized opening 16 in leg 6 for engagement with the mounting nut 18. It will be apparent that by this arrangement, the switch 10 may be pivotally adjusted about pin 12 to provide allowance for the setting of the switch and for variable dimensional tolerances. As shown in FIGURE 4, rotation of nut 18 onto pin 14 will serve to clamp switch 10 in the desired position. Switch 10 has suitable terminals 20 for connection in the circuit'to be controlled. While switch 10 is preferably a micro-switch so that a minimum of movement is necessary, any suitable switch maybe used in the practice of this invention. Switch 10 has a switch but ton 22 which closes the switch when moved inwardly and opens the switch when moved outwardly. Button 22 is biased outwardly to the open position and has its inward movement limited at the switch closing position. Switches of this type are well known and further descriptionthereof is deemed unnecessary.

An actuating lever is pivotally mounted on pin 12. The actuating lever comprises a base portion 24 joined by a pair of spaced arms 26 and 28 adapted to contain the switch 10 therebetween. Pin 12 extends through open- Patented June 9, 1964 ings in arms 26 and 28 to provide a pivotal support for the actuating lever. An arm 30 extends from the arm 28 through an opening 31 in leg 4. Arm 30 may be manually pressed to cause pivotal movement of the actuating lever as will be hereinafter described.

A pin 32 projects through an opening in base 24 for threaded engagement into a nut plate 34. Strung on pin 32 between the nut plate 34 and the head of the pin are a leaf spring 50, the base 24 of the actuating lever, a permanent disc magnet 36, an adjustable shunt plate 38,

an electromagnet core 40, a pole member 42, a spacer plate 46 and a washer 48. Pin 32 is threaded into nut plate 34 to clamp the elements strung on pin 32 together and thus support these elements on the actuating lever for movement therewith. Projecting from thebase 24 as an integral part of the actuating lever is a pole member 44 which has two right angle bends which are suitably reinforced by indentations 45 to provide a rigid structure which is not easily bent. The ends of pole members 42 and 44 project through'openings in spacer plate 46 which is made of a non-magnetic material such as brass. The ends of pole members 42 and 44 provide a gap which will be closed in a manner to be hereinafter described to complete a magnetic circuit. Spring 50 projects into an opening 52 provided between bent portions 54 of-leg 4. Leaf spring 50 is constructed to bias the actuating lever and the apparatus supported thereby in a neutral position as viewed in FIGURE 1.

Core 40 has a winding 56 thereabout which is suitably connected to the circuit to be controlled'so as to be responsive thereto. The coil is designed for the operating level desired, the number of ampere turns being chosen in accordance with the magnetic circuit design. A non-magnetic actuator pin 58 extends through suitable openings in pole member 44 and spacer 46 for axial movement relative to the switch 10. The actuator pin 58 is positioned. to engage, at one end thereof, switch button 22 and carries an armature 60 at the other end thereof which projects through spacer 46. Armature 60 is constructed to provide a bridge between the ends of the pole members 42 and 44 and, of course, is contactable therewith. Actuator pin 58 carries an adjusting nut'62 which is axially movable relative to pin 58 upon rotation of this nut. Pin 58 and nut 62 are made of a suitable aluminum alloy which has non-magnetic properties. A spring 64 is mounted on pin 58 in compression between pole member 44 and nut 62. Spring 64 thus biases the pin 58 in a direction tending to move the armature 60 away from the ends of pole members 42 and 44. This separating movement is limited by a stop member 66 formed on leg 4 to underlie the end of pin 58. The spring load of spring 64 is adjustable by changing the position of nut 62 to provide the desired force on armature 60. A magnetic circuit is thus provided through pole member 42, core 40, adjustable shunt member 38, permanent magnet 36, base 24, pole member 44 and armature 60 all of which are constructed of material having magnetic properties. Permanent magnetism is supplied to the circuit by the magnet 36. This magnetism is capable of being neutralized by the effect of the magnetic field produced by the electromagnet which neutralization will occur during circuit breaker operation. The permanent magnet 36 is of the type which will permit such magnetic neutralization and is made of a ceramic material such as one of the barium ferrites, or such as is commercially available under the trademarks Indox 1, Cromag, or the like having a high coercive force. Permanent magnets of this type have special characteristics of which those utilized here are the following:

The permanent magnetism is not destroyed even though the magnet is subjected to an opposing field which serves not only to reduce the net magnetic field to zero but which may provide a considerable reversal of field. When such a magnetizing field is removed, the permanent magnet returns to and maintains its original strength. Utilized here, as will become apparent, is the neutralizing of the permanent magnet by an electromagnet to reduce the net magnetic field to the point at which the holding force on armature 60 is less than the combined force of spring 64 and switch button 22.

Another property of ceramic magnets of this type is that of the retention of strong magnetism when the magnetic field is across a relatively short dimension, suchas between the faces of the magnet 36. In other words, one face of the magnet constitutes the north pole of the magnet and the other face the south pole. As will be evident therefore from FIGURE 1, the permanent magnet 36 will provide a north pole at one of the pole members 42 and 44 and a south pole at the other of such pole members.

The adjustable shunt member 38 serves to increase or decrease the amount of flux in the magnetic circuit to permit fine adjustment of the power required to operate the electromagnet. The shunt member 38 is adjustable to vary the gap between an arm portion 68 thereof and the pole member 44. The gap adjustment is provided by the bending of arm 68 to vary the spacing between the end thereof and pole member 44. Arm 68 serves as an additional pole member in a magnetic circuit which is in parallel to the magnetic circuit previously described. This parallel magnetic circuit passes through shunt member 38, permanent magnet 36, base 24, pole member 44, and across the gap between arm 68 and the pole member 44. It will be apparent that by varying the gap between arm 68 and pole member 44, the amount of flux in the magnetic control circuit may be varied.

The drawing illustrates the normal circuit-closing position of the apparatus. In this position, the armature 60 is held in contact with the pole members 42 and 44, against the action of spring 64 and switch button 22, by the magnetic field provided by the magnetic circuit including the permanent magnet 36. Leaf spring 50 maintains. the actuating lever and the parts supported thereby in a position wherein the actuating pin 58 depresses the switch button 22 to an inward position by which the switch is held closed. When the apparatus is to function as a .circuit breaker, the switch 10 will be suitably connected in the circuit to be controlled.

If it is desired to manually break the circuit, the arm 30 is moved manually in a counterclockwise direction about pin 12. This will cause a corresponding movement of the actuating lever of which arm 30 is an integral part and, of course, a corresponding movement of pole members 42 and 44. While the pole members 42 and 44 will tend to cause a corresponding movement of armature 60 and actuating pin 58 by reason of the magnetic attraction between pole members 42 and 44 and armature 60, the switch 10 is constructed so that the switch button has only a limited extent of movement beyond the switch closing position and will thus prevent counterclockwise movement of the pin 58 and the armature 60 along with the pole members 42 and 44. Thus, the magnetic contact between the armature 60 and pole members 42 and 44 will be broken. When this occurs, the magnetic attraction between the pole members 42 and 44 and the armature 60 is so reduced that the spring 64 is operative to move the actuator pin 58 away from the switch 10 until arrested by the stop 66. Since the actuator pin 58 no longer holds the switch button 22 inwardly, the switch button 22 will move outwardly in accordance with its bias to the switch opening position thereby to break the circuit.

While the above-described manual circuit breaking operation is not the normal operation of this apparatus, it does not provide a convenient switch to open the circuit.

In the normal circuit breaking operation of the apparatus, the parts will be initially positioned as shown in the drawing with the switch 10 being held closed by reason of the magnetic field supplied by the permanent magnet 36 holding the armature 60 in the attracted position. The

coil of the electromagnet is connected in a suitable manner to be responsive to a condition of a circuit to be controlled so that it will provide an electromagnetic field which will neutralize the permanently induced magnetic circuit through poles 42 and 44 (i.e., reduce the net magnetic field towards, to, or through zero) when the desired overload condition exists in the circuit to be controlled. When the overload condition exists, the current flowing through the coil of the electromagnet will reduce the flux flow in the permanently induced magnetic circuit including pole members 42 and 44 to the point at which the spring load acting on the shunt 60 through actuator pin 58 is greater than the magnetic attraction load on the shunt 66). This condition may exist when the permanent magnet field is reduced only part way to zero. When this occurs, armature 66 will be released and will move away from the switch 10 until arrested by the stop 66. Accordingly, the switch button 22 may move outwardly under its normal bias to the switch opening position to thereby break the circuit.

It will be apparent in a direct current application, the current through the electromagnet coil 56 must be in a direction to provide a magnetic field opposing the permanent magnet field in order to provide for release of armature 60. In the case of alternating current operation, the magnetic field neutralization will occur during the portion of the alternating current cycle at which the current is flowing through the coil 56 in the proper direction to provide the opposing magnetic field.

The apparatus is constructed so that the actuator pin 58 will remain in its release position and thus the switch 10 in its open position even after the coil 56 is deenergized even though the permanent magnet 36 creates a magnetic flux between pole members 42 and 44, which magnetic flux produces an attracting force on the armature 60. This result is attained since the armature 60 is arrested by the stop 66 at a position in which the armature 60 is spaced from the pole members 42 and 44 a distance so that the magnetic attracting force is insuflicient to overcome the separating force provided by the spring 64. It will be noted that the position of stop 66 is adjustable by bending the same, as is illustrated by the dashed lines in FIGURE 4. This permits accurate adjustment of this spacing between the armature 60 and the pole members 42 and 44 at the released position.

The apparatus is manually resettable to the normal position by manually actuating arm 30 in a clockwise direction about pin 12, as viewed in FIGURE 1. Such actuation causes a clockwise movement of both the actuating lever and the parts supported thereby against the counterclockwise bias of spring 50. Thus, pole members 42 and 44 may be moved into contact with the armature 60. When this occurs the magnetic attraction between the armature 60 and the pole members 42 and 44 is greater than the separating force provided by spring 64. It will be noted that at this time the switch button 22 is in its normal position opening the switch 10. When the arm 30 is released, the leaf spring 50 will cause a counterclockwise return movement of the entire assembly including the actuating lever, the parts supported thereby and the pin 58 and armature 60. During this counterclockwise return movement, the actuator pin 58 will contact the switch button 22 and force the same inwardly to again place the switch 10 in the closed position thereof. The parts are now in normal position as is illustrated in the drawing.

An advantage of the circuit breaker in accordance with this invention is that it avoids the possibility of manual closure of the circuit during an overload condition. Thus, with the parts in the normal overload position with armature 60 released, if the actuating lever is depressed to cause engagement of the pole members 42 and 44 with the armature 60 and then released, the armature 60 will not return with the pole members toward the switch 10. Instead, the armature 60 will remain in its released positron resting on stop 66 since the magnetic circuit through the pole members 42 and 44 is still sufliciently neutralized by the electromagnet because of the existence of the overload condition so that the spring load on armature 60 biasing the same to the released position exceeds the magnetic attraction load. Thus, the armature remains in its released position and switch will remain inits circuit breaking position. A

It will be apparent that the circuit breaker in accordance with this invention may have many modifications without departing from the scope of the invention. For example, the circuit breaker may be used to provide voltage, current, or voltage and current protection.

Also, the circuit control in accordance with this invention may have many modifications. For example, the rise of current in the electromagnet winding may be utilized to close another circuit or to both open and close other circuits. This may be accomplished by providing a double throw microswitch which may be connected to both open and overload circuit and close an alarm circuit.

It is thus not desired to be limited except as by the following claims.

What is claimed is:

1. A circuit breaker comprising switching means adapted for connection in the circuit to be controlled including a control member movable between circuit making and circuit breaking positions, and means for actuating said control member between said positions thereof including means providing a magnetic circuit having a pair of pole members, said magnetic circuit including a magnet providing a magnetic field, armature means responsive to the magnetic field of said magnetic circuit and movable between an attracted and a released position relative to said pole members, means for transmitting movement of said armature means to said control member, said armature means causing movement of said control member between required said controlling positions upon movement of said armae ture means between said attracted and said released positions thereof, said armature means being biased toward said released position, said magnetic circuit means normally providing a magnetic force to hold said armature means in said attracted position, and means for neutralizing said magnetic circuit to reduce said holding force, said bias of said armature means causing movement thereof from said attracted position to said released position in response to neutralization of said magnetic circuit, said armature means being serially connected in said magnetic circuit and movable to contact said pole members in said attracted position and to be spaced relative to said pole members in said released position, said magnetic fieid provided by said magnetic circuit being insufficient to magnetically attract said armature from said released position to said attracted position.

2. A circuit breaker as claimed in claim 1 wherein said magnetic'circuit means includes a permanently magnetized ceramic magnet.

3. A circuit breaker as claimed in claim 1 wherein said neutralizing means includes an electromagnet for producing a magnetic field to neutralize the magnetic field of said magnetic circuit means.

4. A circuit breaker as claimed in claim 1 wherein said magnetic circuit means includes a permanently magnetized ceramic magnet and said neutralizing means includes an electromagnet associated with said permanent magnet for producing a magnetic field when energized to neutralize the permanent field of said magnet.

5. A circuit breaker comprising switching means adapted for connection in the circuit to be controlled including a control member movable between circuit making and circuit breaking positions, and means for actuating said control member between said positions thereof including means providing a magnetic circuit having a pair of pole members, said magnetic circuit including a magnet providing a magnetic field, armature means responsive to the magnetic field of said magnetic circuit and movable between an attracted and a released position relative to said 6 pole members, means for transmitting movement of said armature means to said control member, said armature means causing movement of said control member between said controlling positions upon movement of said armature means between said attracted and said released positions thereof, said armature means being biased toward said released position, said magnetic circuit means normally providing a magnetic force to hold said armature means in said attracted position, means for neutralizing said magnetic circuit to reduce said holding force, said bias of said armature means causing movement thereof from said attracted position to said released position in response to neutralization of said magnetic circuit, said armature means being serially connected in said magnetic normal position thereof against the bias thereoftoward contact with said armature means toincrease the magnetic attracting force between said pole members and said armature means an amount so that said armature means is held in contact with said pole members by the magnetic field of said magnetic circuit means.

6. A circuit breaker comprising switching means adapted for connection in the circuit to be controlled including a control member movable between circuit making and circuit breaking positions, and means for actuating said control member between said positions thereof including means providing a magnetic circuit having a pair of pole members, said magnetic circuit including a magnet providing a magnetic field, armature means responsive to the magnetic field of said magnetic circuit and movable be tween an attracted and a released position relative to said pole members, means for transmitting movement of said armature means to said control member, said armature means causing movement of said control member between said controlling positions upon movement of said armature means between said attracted and said released positions thereof, said armature means being biased toward said released position, said magnetic circuit means normally providing a magnetic force to hold said armature means in said attracted position, means for neutralizing said magnetic circuit to reduce said holding force, said bias of said armature means causing movement thereof from said attracted position to said released position in response to neutralization of said magnetic circuit, a frame, means fixedly positioning said switching means on said frame, a lever movably mounted on said frame and means mounting said magnetic circuit means on said movable lever for movement therewith.

7. A circuit breaker as claimed in claim 6, including an adjustable stop means on said frame for positioning said armature means in said released position.

8. A circuit breaker comprising switching means adapted for connection in the circuit to be controlled including a control member movable between circuit making and circuit breaking positions, and means for actuating said control member between said positions thereof including means providing a magnetic circuit having a pair of pole members, said magnetic circuit including a magnet providing a magnetic field, armature means responsive to the magnetic field of said magnetic circuit and movable between an attracted and a released position relative to said pole members, means for transmitting movement of said armature means to said control member, said armature means causing movement of said control member between said controlling positions upon movement of said armature means between said attracted and said released positions thereof, said armature means being biased toward said released position, said magnetic circuit means normally providing a magnetic force to hold said armature means in said attracted position, and means for neutralizing said magnetic circuit to reduce said holding force, said bias of said armature means causing movement thereof from said attracted position to said released position in response to neutralization of said magnetic circuit, said magnetic circuit including a magnetic shunt member manually movable to vary the strength of the magnetic field of said magnetic circuit means.

9. A circuit breaker comprising switching means adapted for connection in the circuit to be controlled including a control member movable between circuit making and circuit breaking positions, and means for actuating said control member between said positions thereof including means providing a magnetic circuit having a pair of pole members, said magnetic circuit including a magnet providing a magnetic field, armature means responsive to the magnetic field of said magnetic circuit and movable between an attracted and a released position relative to said pole members, means for transmitting movement of said armature means to said control member, said armature means causing movement of said control member between said controlling positions upon movement of said armature means between said attracted and said released positions thereof, said armature means being biased toward said released position, said magnetic circuit means normally providing a magnetic force to hold said armature means in said attracted position, means for neutralizing said magnetic circuit to reduce said holding force, said bias of said armature means causing movement thereof from said attracted position to said released position in response to neutralization of said magnetic circuit, said magnetic field provided by said magnetic circuit being insuificient to magnetically attract said armature from said released position to said attracted position, and means for resetting said armature to said attracted position from said released position including means for moving said pole members toward said armature in its releasedposition to a position in which the magnetic field provided by said magnetic circuit means is insuflicient to attract said armature.

References Cited in the file of this patent UNITED STATES PATENTS 2,904,653 Leo Sept. 15, 1959 72,915,681 Troy Dec. 1, 1959 2,919,324 Schucssler 'Dec. 29, 1959 2,951,134 Lazich Aug. 30, 1960 2,952,755 Brinker et al Sept. 13, 1960 2,975,252 Juptner Mar. 14, 1961 

1. A CIRCUIT BREAKER COMPRISING SWITCHING MEANS ADAPTED FOR CONNECTION IN THE CIRCUIT TO BE CONTROLLED INCLUDING A CONTROL MEMBER MOVABLE BETWEEN CIRCUIT MAKING AND CIRCUIT BREAKING POSITIONS, AND MEANS FOR ACTUATING SAID CONTROL MEMBER BETWEEN SAID POSITIONS THEREOF INCLUDING MEANS PROVIDING A MAGNETIC CIRCUIT HAVING A PAIR OF POLE MEMBERS, SAID MAGNETIC CIRCUIT INCLUDING A MAGNET PROVIDING A MAGNETIC FIELD, ARMATURE MEANS RESPONSIVE TO THE MAGNETIC FIELD OF SAID MAGNETIC CIRCUIT AND MOVABLE BETWEEN AN ATTRACTED AND A RELEASED POSITION RELATIVE TO SAID POLE MEMBERS, MEANS FOR TRANSMITTING MOVEMENT OF SAID ARMATURE MEANS TO SAID CONTROL MEMBER, SAID ARMATURE MEANS CAUSING MOVEMENT OF SAID CONTROL MEMBER BETWEEN SAID CONTROLLING POSITIONS UPON MOVEMENT OF SAID ARMATURE MEANS BETWEEN SAID ATTRACTED AND SAID RELEASED POSITIONS THEREOF, SAID ARMATURE MEANS BEING BIASED TOWARD SAID RELEASED POSITION, SAID MAGNETIC CIRCUIT MEANS NORMALLY PROVIDING A MAGNETIC FORCE TO HOLD SAID ARMATURE MEANS IN SAID ATTRACTED POSITION, AND MEANS FOR NEUTRALIZING SAID MAGNETIC CIRCUIT TO REDUCE SAID HOLDING FORCE, SAID BIAS OF SAID ARMATURE MEANS CAUSING MOVEMENT THEREOF FROM SAID ATTRACTED POSITION TO SAID RELEASED POSITION IN RESPONSE TO NEUTRALIZATION OF SAID MAGNETIC CIRCUIT, SAID ARMATURE MEANS BEING SERIALLY CONNECTED IN SAID MAGNETIC CIRCUIT AND MOVABLE TO CONTACT SAID POLE MEMBERS IN SAID ATTRACTED POSITION AND TO BE SPACED RELATIVE TO SAID POLE MEMBERS IN SAID RELEASED POSITION, SAID MAGNETIC FIELD PROVIDED BY SAID MAGNETIC CIRCUIT BEING INSUFFICIENT TO MAGNETICALLY ATTRACT SAID ARMATURE FROM SAID RELEASED POSITION TO SAID ATTRACTED POSITION. 